1. Field of the Invention
The present invention relates to a powered slide rail device for adjustably moving a vehicle seat in forward and backward directions under the drive force of an electric motor and associated electric element.
2. Description of Prior Art
FIG. 1 shows a conventional powered slide rail device (102) on which a front seat (100) and a rear seat (101) are slidably mounted. This kind of slide rail device is frequently used in a vehicle having a long and wide cabin, such as a minivan, and typically comprised of a long lower rail, an upper rail slildably engaged with the long lower rail, a lead screw disposed in and along the long lower rail in the longitudinal direction thereof, a nut member rotatably disposed in the upper rail, the nut member being threadedly engaged about a part of such long lead screw, and a motor connected with the nut member. Normal and reverse operation of the motor causes forward and backward movement of the upper rail along the lower rail to adjustingly position a seat on the slide rail device at a desired point.
In most cases, such powered slide rail device is one mechanical part of a powered vehicle seat which includes a plurality of electric motors associated with a seat cushion tip-up mechanism, reclining device and so forth. Hence, as shown in FIG. 1, a long electric cable (103), which is electrically connected between the seat and a power source, extends along the long lower rail or a floor of vehicle, so that the seat can smoothly move on and along the long lower rail.
But, the long electric cable stands in the way of a passenger who sits on the seat, or narrows the floor area on which the passenger can rest his or her feet. It is therefore frequently the case that the wire cable is cut off by the passenger's feet, or partly broken to cause a short circuit therein.
Solution to such problem has been found for example in the Japanese Laid-Open Patent Publication No. 8-332906 which discloses a powered slide rail device wherein an electrode plate, electrically connected with a power supply, is fixed to and along the inner wall of a lower rail of the slide rail device, and a contact brush, electrically connected with a motor, is provided on an upper rail slidably engaged with the lower rail. The contact brush is kept in contact with the electrode plate, so that an electric current flows from the power supply side (e.g. an electric connector for powered seat, which is provided on a control box) to the motor. With that structure, the electric current path is not exposed outwardly like the afore-said electric cable.
Nonetheless, in the foregoing prior art, the electrode plate extending along the lower rail inner wall is perpendicular with the flat plane of floor, and the contact brush is provided on a movable connector so as to project horizontally and slidably contact such perpendicular electrode plate. This conventional arrangement is found defective in that a slidable contact between the contact brush and electrode plate is not complete, and thus, it is highly possible that a loose connection will occur between those contact brush and electrode plate due to a vibration of a vehicle body or a deformation of the upper and lower rails in a collision case or the like.